This invention relates to a D.C. controlled attenuator. More specifically, this invention relates to a D.C. controlled video attenuation circuit (contrast control) with three tracking channels that may be used, for example, as a tracking contrast control in an RGB video monitor.
Several systems have been developed for use in controlling contrast in high quality television monitors. One system, which involves the use of complex circuitry, involves adding and monitoring a flag on the back porch of the horizontal sync pulse. Another system, which is bulky and expensive, uses three banks of resistors controlled by a multi-position three ganged switch.